Coaxial injector for reaction motors

ABSTRACT

A coaxial injector particularly suited for use in mixing liquid propellants within combustion chambers of reaction motors, characterized by a first annular orifice, of a fixed dimension, adapted to deliver liquid oxidizer in an outwardly diverging conical sheet circumscribed by a second annular orifice, also of a fixed dimension, adapted to deliver an outwardly converging conical sheet of liquid fuel, whereby the sheets are caused to experience momentum exchange at an annular intersection for thereby developing a homogeneous mixture sheathed within a layer of a fuel-rich mixture for cooling the walls of the associated combustion chamber, a feature of the injector being an integration of injector components into an all-welded, unitary structure having empirically established propellant mixing characteristics.

United States Patent Paine et al.

[ 51 May 16, 1972 154] COAXIAL INJECTOR FOR REACTION MOTORS [22] Filed: Mar. 16, 1970 [21] Appl.No.: 19,585

3,232,049 2/1966 Rhodes ..60/39.46 X 2,453,378 11/1948 Lubbock ..60/258 X 3,421,700 1/1969 Seamans ..60/39.74 A 2,714,286 8/1955 Zucrow.... ..60/258 2,972,227 2/1961 Allen ..60/258 Primary ExaminerDouglas Hart Attorney-J. H. Warden, Monte F. Mott and G. T. McCoy [5 7] ABSTRACT A coaxial injector particularly suited for use in mixing liquid propellants within combustion chambers of reaction motors, characterized by a first annular orifice, of a fixed dimension, adapted to deliver liquid oxidizer in an outwardly diverging conical sheet circumscribed by a second annular orifice, also of a fixed dimension, adapted to deliver an outwardly converging conical sheet of liquid fuel, whereby the sheets are caused to experience momentum exchange at an annular intersection for thereby developing a homogeneous mixture sheathed within a layer of a fuel-rich mixture for cooling the walls of the associated combustion chamber, a feature of the injector being an integration of injector components into an allwelded, unitary structure having empirically established propellant mixing characteristics.

4 Claims, 5 Drawing Figures PATENTEDMM 161972 sum 2 OF 2 LARRY L. LARSON IN V f N TOR w 1' ATTORNEYS COAXIAL INJECTOR FOR REACTION MOTORS ORIGIN OF INVENTION The invention described herein was made in the performance of work under a NASA contract and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, Public Law 85-568 (72 Stat. 435; 42 USC 2457).

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention generally relates to coaxial injectors for delivering propellants to reaction motors, and more particularly to an improved coaxial injector of an all-welded, unitary configuration having empirically established characteristics.

2. Description of the Prior Art The use of injectors in simultaneously delivering fuels and oxidizers to combustion chambers of the reaction motors is notoriously old. Normally, a liquid fuel and its associated oxidizer simultaneously are injected from separate orifices into an associated combustion chamber in a manner such that the fuel and its oxidizers are brought into physical conta for thereby achieving a desired mixing and a resulting oxidation of the fuel.

Where oxidation of a fuel occurs over an extended period, the resulting temperatures developed along the surfaces of the wall of the combustion chamber tend to become excessive. Such temperatures have known deleterious effects, including an introduction of erratic thrust and ultimate destruction of the motor. In order to control attained temperatures, attempts have been to establish auxiliary cooling systems. However, such systems tend to be excessively complex, bulky and impose pay-load restraints. Successful attempts have been made to cool the motors by establishing a fuel-rich layer of propellant mixture along the wall of the combustion chamber in order that the layer be provided to serve as a protective barrier for inhibiting a transfer of heat to the wall from the gases of combustion. However, this normally requires that an injector head be provided with a multiplicity of discrete and radially aligned injection parts. In practice, fabrication of such heads introduces added cost, since the components of the injectors must be machined to close tolerances and multiple injector elements necessarily increase the weight and complexity of the resulting system.

Suitable propellants currently are available for use in systems wherein limited variation in mixing characteristics of fabricated injectors can be tolerated. Normally, however, such propellants must be stored at cryogenic temperatures. Where a system is employed over extended periods of time, the associated weight penalties involved in accommodating a storage of propellants at cryogenic temperatures are highly undesirable. While high-energy propellants, such as, for example, oxygen difluoride (OB) and diborane (B H,,) can be stored at semi-cryogenic temperatures, the injectors require accurately predictable mixing characteristics. This particularly is true where the fuel is to be employed in establishing a thermal barrier along the internal surfaces of the chamber walls.

Therefore, there currently exists a need for a practical, lowcost, coaxial injector having highly predictable propellant delivery and mixing characteristics, capable of establishing a thermal barrier and efiiciently mixing high-energy liquid propellants of types adapted to be stored and maintained at temperatures above cryogenic.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a coaxial propellant injector having improved propellant delivery and mixing characteristics.

Another object is to provide an improved coaxial liquid propellant injector of a unitary configuration having empirically established injection and mixing characteristics.

Another object is to provide coaxial injectors for reaction motors fabricated into an all-welded and fully integrated configuration including a pair of concentric orifices adapted to deliver reversely related conical sheets of fuel and oxidizer to a momentum-exchanging intersection, whereby a high-quality mixture of fuel and oxidizer is provided and encased in a protective sheath of fluid-rich mixture which serves as a thermal barrier for the high-quality mixture.

These and other objects and advantages are achieved through the use of an all-welded, unitary coaxial propellant injector including concentric, annular orifices each having empirically established characteristics adapted to deliver reversely related, intersecting streams as conical sheets of selected fuels and oxidizers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially sectioned, perspective view of a coaxial injector embodying the principles of the present invention.

FIG. 2 is a partially sectioned side elevation of the injector taken generally along line 2-2 of FIG. 1.

FIG. 3 is a partially sectioned elevation of the injector of FIG. I mounted in an assembly jig employed in empirically determining the injection and mixing characteristics of the injector of FIG. 1.

FIGS. 4 and 5 are fragmentary, partially sectioned, views illustrating a progressive positioning of the injector components during assembly of the injector.

DESCRIPTION OF THE PREFERRED EMBODIMENT (General Description Of The Coaxial Injector) Referring now to the drawings wherein like reference characteristics designate like or corresponding parts throughout the several views, there is shown in FIG. 1 a coaxial injector 10 embodying the principles of the present invention. The injector 10 includes an injector body 11 adapted to be mounted in an operative relationship relative to an end wall 12 of a combustion chamber of a reaction motor, not designated. While the combustion chamber forms no part of the instant invention, it is to be understood that, in practice, such chambers receive liquid propellants which therein are mixed for purposes of achieving thrust. It is to be understood that various means may be employed in mounting the injector 10 adjacent to the chamber. For example, an annular flange 14 adapted to be seated on an annular shoulder 16, fonned in the wall 12 of the combustion chamber, serves quite satisfactorily for. this purpose.

The injector 10 includes a propellant injection cone 18 of a generally flared, truncated conical configuration coaxially related to the combustion chamber and adapted simultaneously to inject selected fuels and oxidizers therethrough for establishing within the chamber an homogeneous propellant mixture. It will be appreciated that the angle of inclination for the injection cone I8 is, in practice, varied as desired. However, it is important to note that where the injector I0 is employed in an environment wherein it is desired that a layer of a fuel-rich mixture of fuel and oxidizer be established along the surface of the wall 12 in order to provide a thermal barrier for protecting the wall, the cone 18 is provided with an outward flared angle of inclination suitable for accommodating a diverging flow of propellant as it is established between the cone and the wall.

Fuel in a liquid state is delivered to the injector 10 through a pair of fuel conduits 20 coupled between a suitable source of fuel, not shown, and a spaced pair of fuel passageways 22 through which the fuel is delivered to a fuel metering chamber 24. The chamber 24 is formed as an annular recess and includes an annular wall 25 of a generally truncated conical configuration communicating with the injection cone 18, at a common plane of truncation defining therebetween an opening which serves as a fuel metering port generally designated 26. The terminal portion of each of the passageways 22 is extended radially from the metering chamber 24 so that oppositely directed streams of fuel simultaneously are delivered to the metering chamber along radially directed paths.

From the chamber 24 there is extended a coaxially related bore 28 which terminates in the plane of an outer surface 30, relative to the chamber. Within the bore 28 there is seated a metering plug 32, having an elongated body 33 terminating near the surface 30 and rigidly secured to the body 11. It is to be understood that the relationship of the body 11 and the metering plug 32 fixedly is established, preferably through an annular weld bead or seam 34. Consequently, the plug is integrated with the body 11 for forming a single unitary element.

The plug 32 also includes a metering tip 35 having a truncated conical metering surface 36. The tip 35 concentrically is extended through the fuel metering chamber 24 into the fuel metering port 26 for thereby establishing a fuel injection orifice 37 of an annular configuration. The angle of inclination of the adjacent conical surfaces of the metering chamber 24 and the tip 35 of the metering plug 32 are quite similar so that once these surfaces selectively are positioned in a spaced, concentric relationship, there is established a conical passageway through which a conical stream of fuelis delivered to the fuel injection orifice 37. Due to the inclination of the thus established passageway, the fuel is delivered through the orifice 37 as an outwardly converging conical sheet of fuel.

As readily can be appreciated, the quantity and velocity of fuel delivered by the injection orifice 37 is dictated by axially positioning the metering plug 32, whereby the metering surface 36 of the tip 35 selectively is displaced from the wall 25. Since the metering plug 32 and the body 11 are welded at the seam 34, for thereby integrating the plug 32 with the body 11, the injection characteristics of the fuel injection orifice 37 permanently are established.

Liquid oxidizer is delivered to the injector through a tubular member 38. The tubular member 38 is seated within a bore 40 concentrically extended through the metering plug 32. This member also is welded to the metering plug 32, at a seam 41, for thus integrating the body 11, the tubular member 38 and the plug 32 into a single-element, unitary structure.

The bore 40 also is provided with an outwardly flared terminal chamber 42, defined by a wall 43 of an outwardly flared, truncated conical configuration. The base of the terminal chamber 42 defines the periphery of an oxidizer discharge port 44. Adjacent to the terminal chamber of the bore 40, there is provided an annular groove 45 which establishes peripheral wall portions of an annular oxidizer manifold chamber 46. The manifold chamber 46 communicates with the terminal chamber 42 along the chambers plane of truncation. in practice, the external surface of the tubular member 38 also is provided with an annular relief 47 which is a mirror image of the groove 45 and cooperates therewith in a manner such that the walls thereof define the internal surfaces of the annular manifold 46.

The oxidizer conduit or tubular member 38 terminates in a conical protuberance which serves as an oxidizer metering plug 48. This metering plug includes an external metering surface 49, also of a substantially truncated conical configuration, having an angle of inclination similar to that of the wall 43. The metering plug 48 concentrically is disposed within the chamber 42 whereby the oxidizer discharge port 44 also is caused to assume an annular configuration. Therefore, it is to be understood that, in operation, a flow of oxidizer is established between the surface of the wall 43 and the metering surface 49 of the plug 48 and caused to exit the oxidizer discharge port 44. Due to the inclination of the surfaces of the metering plug 48 and wall 43 the oxidizer is discharged as an outwardly diverging conical sheet of oxidizer.

A plurality of radially extended openings 52 serve as conduits for directing oxidizer under pressure into the manifold chamber 46 so that as an oxidizer is delivered through the tubular member 38, it is discharged from the conduit into the annular manifold chamber 46, by way of the radial openings 52. The oxidizer then is delivered from the chamber 46,

between the metering surface 49 of the metering plug 48 and the wall 43 of the temiinal portion 42 of the bore 40, for ultimate injection through the oxidizer discharge port 44. Hence, the flow characteristics for the oxidizer, including the quantity and velocity of the stream of oxidizer discharged through the oxidizer discharge port 44, are dictated by the positioning of the metering plug 48 relative to the surface of the wall 43 and this positioning of the metering plug is permanently established at the weld head or seam 41.

Since the annular oxidizer discharge port 44 is circumscribed by the annular fuel injection orifice 37, it should readily be apparent that the outwardly diverging conical sheet of injected oxidizer intercepts the inwardly converging conical sheet of fuel injected by the fuel injection orifice 37 at an annular intersection, not designated. Due to the effect of the kinetic energy of the streams of oxidizer and fuel, their directions of flow are altered as mixing of the fuel and oxidizer occurs. Due to the volumetric flow of the fuel and oxidizer, and the established relative velocity of the streams, portions of the conical sheet of fuel are deflected toward the adjacent wall of the associated combustion chamber for establishing a fuelrich, cooler burning region along the chambers wall 12. Thus, a mixture pattern resulting from the intersection of the cones establishes a fuel-rich layer on the outboard side, and oxidizerrich region on the inboard side of the resulting body of propellant mixture.

Since the flow characteristics of the fuel injection orifice 37 and the oxidizer discharge port 44 are functions of the positioning of the fuel metering plug 32 and the oxidizer metering plug 48, it is imperative that their positioning be achieved prior to the welding of the metering plug 32 to the body 11 and the welding of the tubular member 38 to the metering plug 32 for integrating the injector 10 into a unitary, singleelement coaxial injector.

(Assembly Of The Coaxial injector) Positioning of the metering plugs 32 and 48, preparatory to welding, is achieved employing an assembly jig 60, FIG. 3. The jig 60 is provided with a base plate 62 having an annulus 64 for receiving therein the injection cone 18. The base plate 62 is mounted within the wall of a suitable observation chamber, not shown, which is utilized in collecting fluid operatively delivered through the injection cone 18. As a practical matter, a suitable monitoring system, also not shown, is included within the chamber in order that the propellant injection characteristics of the injector 10 may be observed during its assembly and related test operations.

The injector 10 is secured in place within the plate 62 through a plurality of peripheral clamps 66, each having a screw-threaded mounting stud 67 suitably extended therethrough. The clamps 66 serve to engage and rigidly support the injector 10 in an operational position relative to the plate 62, as the studs threadably couple the clamps with the base plate.

Astride the injector 10 there is a support bracket 68 of generally inverted U-shaped configuration having a laterally extended support plate 70 including a vertically extended screw-threaded opening 72 coaxially related with the tubular member 38. Threadably secured within the opening 72 there is an axially extendible micrometer 74 of a suitable design. In practice, the micrometer includes an elongated shaft 76 extended through a concentric bushing 77 seated in the opening 72. It is to be understood that as the micrometer 74 is torqued, the shaft 76 axially is displaced and the direction of displacement is dictated by the direction of the torque. As a practical matter, the distal end of the shaft 76 is provided with a support ball-and-socket coupling 78 fixed to an hydraulic fitting 80 having an angularly configured passageway 82. The fitting 80 is, in practice, coupled with a tubular fitting 84 mounted at the adjacent end of a tubular conduit 86 which couples the injector 10 to a suitable source of fluid, not shown.

When assembled, the tubular member 38 is tack-welded to the output side of the fitting 80 in order that axial displacement is imparted to the tubular member 38 through a torquing manipulation of the micrometer 74. Prior to assembly, the metering plugs 32 and 48 are seated in engagement with the conical surfaces adjacent thereto in a manner such as to close and thus totally eliminate the orifices 37 and 44. In order to assure that the plug 32 remains in its seated disposition, a plurality of restraining clamps 88, having screw-threaded mounting studs 90, are secured to the body 11. These clamps are employed as a retraction stop for assuring that the plug 32 remains in a fully seated relationship relative to the adjacent surface of the fuel metering chamber 24 as the tubular member 38 axially is displaced through a manipulation of the micrometer 74.

As best illustrated inFlG. 4, once the injector is secured within the jig 60, the spacing between the adjacent surfaces of the wall 43 and the external surface 49, of the metering plug 48, initially is established for thereby fixing the dimension of the oxidizer port 44. This occurs prior to a positioning of the metering plug 48 relative to the body 11 for fixing the dimension of the fuel injection port 26. As the micrometer 74 is manipulated for forcing the oxidizer conduit or tubular member 38, both upwardly and downwardly, through a bore 40 for thereby increasing the effective dimension of the port 44, fluid is delivered under an established pressure through the conduit 86, the fitting 80, and ultimately to be discharged from the oxidizer discharge port 44 for thereby simulating an injection of fluid oxidizer to a combustion chamber of a reaction motor. As presently employed, water is employed as a substitute for the oxidizer in establishing the operative characteristics of the discharge port 44 during the assembly of the injector 10. Once a satisfactory stream having desired operative characteristics, such as a determinable flow rate and flow pattern, is established the tubular member 38 rigidly is coupled with the plug 32 at the annular weld seam 41.

Having thus established the operative dimensions for the annular oxidizer discharge port 44, the clamp 88 is removed for thus freeing the plug 32 for axial displacement relative to the surface of the bore 28. Through a manipulation of the micrometer 74, for thus displacing the shaft 76 in a selected direction, the body 33 of the plug 32 is elevated so that the surface 36 of the metering tip 35 is lifted from its seated engagement with the surface of the wall 25 of the fuel metering chamber 24. As the tip 35 is lifted it axially is displaced relative to its fuel metering port 26, whereby the fuel injection orifice 37 is established. As the plug 32 is elevated, a fluid is delivered under a given pressure through the fuel passageways 22, by way of suitable fittings 92 interconnected with a source of fluid, also not shown. From the passageways 22, the fluid is directed through the fuel injection orifice 37. As a practical matter, hexane is substituted for fuel during the assembly and testing of the injector 10. As the position of the plug 32 is varied, the injection characteristics of the fuel injection orifice 37 are varied. Once desired flow rates and spray patterns are derived for the fuel injection orifice, the plug 32 is welded to the body 11 of the injector 10, at the seam 34, for thereby integrating the components of the injector 10 into a single-ele ment, coaxial injector, as illustrated in FIG. 5. The injector 10, now welded into a fully integrated, unitary structure is removed from the jig 60 with its propellant delivery charac teristics being fixedly established.

Since the injection characteristics of the injector 10 are empirically established during assembly, variations in manufacturing tolerances can, within practical limits, be accommodated without sacrificing motor efficiency and thrust predictability.

In view of the foregoing, it should readily be apparent that the injector embodying the principles of the present invention is a low-cost, single-element, coaxial injector having improved mixing characteristics capable of utilizing fuel and oxidizers, such as OF: and B H with a high degree of efliciency and predictability.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the illustrative details disclosed.

What is claimed is:

l. A single-element coaxial injector for reaction motors comprising:

A. an injector plate adapted to be mounted within the wall of a combustion chamber of a reaction motor;

B. means defining within said plate a bore terminating in a first outwardly flared segment for communicating with said combustion chamber;

C. a first metering plug seated in said bore and welded to said injector plate for thereby defining a permanently configured, annular fuel injection orifice for delivering a converging conical stream of fuel;

D. means defining an axial bore extending through said first metering plug tenninating in an outwardly flared conical segment concentrically related with said fuel injection orifice; and

E. a second metering plug extended into said axial bore and welded to said first metering plug defining a permanently configured annular oxidizer discharge orifice concentrically related to said annular fuel injection orifice for delivering a diverging conical stream of oxidizer intercepting the conical stream of fuel.

2. A coaxial injector for reaction motors comprising:

A. an injector plate including means defining therein an outwardly flared injection cone;

B. means defining a tubular bore extended through said plate in a coaxial relationship with said injection cone;

C. means defining within said tubular bore a fuel metering chamber of an outwardly converging, truncated conical configuration communicating with said injector cone;

D. means defining a plurality of fuel passageways communicating with the tubular bore;

E. a first elongated metering plug having a cylindrical body and a tapered metering tip disposed within said tubular bore in a manner such that the surface of the tapered tip and the surface of said metering chamber are concentrically related for defining therebetween a fuel injection orifice of an annular configuration for delivering a converging conical sheet of fuel;

F. means defining a concentric bore extended through said metering plug and terminating in an oxidizerdischarge cone of an outwardly flared, truncated, conical configuration;

G. an annular chamber defining a manifold communicating with said oxidizer discharge cone and circumscribing said concentric bore;

H. a unitary tubular member defining an oxidizer delivery conduit seated in said concentric bore and terminating in a second elongated metering plug of an outwardly flared, conical configuration having a metering surface radially spaced from the surface of said oxidizer discharge cone and defining therebetween an annular oxidizer discharge orifice for delivering a diverging conical sheet of fluid oxidizer;

I. means defining within the tubular member a plurality of radially directed openings extending between said conduit and said annular chamber; and

J. a plurality of weld seams integrating the plate, the first metering plug, and the unitary tubular member into a rigid unitary configuration.

3. The injector of claim 2 wherein the position of the metering plug relative to the metering chamber and the tubular member relative to the concentric bore empirically are established for determining the flow characteristics of the fuel injector orifice and the oxidizer discharge orifice.

4. A coaxial injector for liquid propellant reaction motors comprising:

A. an injector plate adapted to be mounted on the wall of a combustion chamber within a reaction motor;

B. a plate having formed therein means defining an injection cone including a discharge opening and an inlet opening of a reduced diameter coaxially related to said discharge opening;

C. a bore extending from said inlet opening through said plate including a conical metering surface defining a first metering chamber adjacent said inlet opening;

D. a first metering plug including an axial bore extended therethrough and terminating in an outwardly flared internal surface defining a second metering chamber of a. conical configuration, and a conically tapered external surface defining a metering needle, said first metering plug being inserted and positioned within said bore in a manner such that the conically tapered external surface thereof is positioned adjacent the metering surface of the first metering chamber as a fluid under pressure is delivered therebetween, for thereby establishing a first annular orifice having empirically determined flow characteristics;

E. a metering shaft having an axial conduit terminating in a plurality of radially directed terminal ports including a terminal protuberance of a conical configuration closing said axial conduit at a point adjacent to said ports and defining a second metering plug seated within the axial bore of said first metering plug in a manner such that the external surface of the second metering plug is related to the outwardly flared internal surface of the first metering plug for defining a fluid passageway therebetween, the axial position of said shaft being achieved concurrently with a delivery of a fluid through the conduit and said fluid passageway for thus establishing an annular discharge orifice having empirically determined flow characteristics;

F. means defining a first weld seam coupling said shaft in place within said axial bore, whereby said shaft and said I first metering plug fixedly are integrated into a unitary configuration; and G. means defining a second weld seam coupling said first metering plug to said plate for thereby fixedly integrating the plate and the metering plugs of said injector into a unitary, single-element coaxial injector. 

1. A single-element coaxial injector for reaction motors comprising: A. an injector plate adapted to be mounted within the wall of a combustion chamber of a reaction motor; B. means defining within said plate a bore terminating in a first outwardly flared segment for communicating with said combustion chamber; C. a first metering plug seated in said bore and welded to said injector plate for thereby defining a permanently configured, annular fuel injection orifice for delivering a converging conical stream of fuel; D. means defining an axial bore extending through said first metering plug terminating in an outwardly flared conical segment concentrically related with said fuel injection orifice; and E. a second metering plug extended into said axial bore and welded to said first metering plug defining a permanently configured annular oxidizer discharge orifice concentrically related to said annular fuel injection orifice for delivering a diverging conical stream of oxidizer intercepting the conical stream of fuel.
 2. A coaxial injector for reaction motors comprising: A. an injector plate including means defining therein an outwardly flared injection cone; B. means defining a tubular bore extended through said plate in a coaxial relationship with said Injection cone; C. means defining within said tubular bore a fuel metering chamber of an outwardly converging, truncated conical configuration communicating with said injector cone; D. means defining a plurality of fuel passageways communicating with the tubular bore; E. a first elongated metering plug having a cylindrical body and a tapered metering tip disposed within said tubular bore in a manner such that the surface of the tapered tip and the surface of said metering chamber are concentrically related for defining therebetween a fuel injection orifice of an annular configuration for delivering a converging conical sheet of fuel; F. means defining a concentric bore extended through said metering plug and terminating in an oxidizer discharge cone of an outwardly flared, truncated, conical configuration; G. an annular chamber defining a manifold communicating with said oxidizer discharge cone and circumscribing said concentric bore; H. a unitary tubular member defining an oxidizer delivery conduit seated in said concentric bore and terminating in a second elongated metering plug of an outwardly flared, conical configuration having a metering surface radially spaced from the surface of said oxidizer discharge cone and defining therebetween an annular oxidizer discharge orifice for delivering a diverging conical sheet of fluid oxidizer; I. means defining within the tubular member a plurality of radially directed openings extending between said conduit and said annular chamber; and J. a plurality of weld seams integrating the plate, the first metering plug, and the unitary tubular member into a rigid unitary configuration.
 3. The injector of claim 2 wherein the position of the metering plug relative to the metering chamber and the tubular member relative to the concentric bore empirically are established for determining the flow characteristics of the fuel injector orifice and the oxidizer discharge orifice.
 4. A coaxial injector for liquid propellant reaction motors comprising: A. an injector plate adapted to be mounted on the wall of a combustion chamber within a reaction motor; B. a plate having formed therein means defining an injection cone including a discharge opening and an inlet opening of a reduced diameter coaxially related to said discharge opening; C. a bore extending from said inlet opening through said plate including a conical metering surface defining a first metering chamber adjacent said inlet opening; D. a first metering plug including an axial bore extended therethrough and terminating in an outwardly flared internal surface defining a second metering chamber of a conical configuration, and a conically tapered external surface defining a metering needle, said first metering plug being inserted and positioned within said bore in a manner such that the conically tapered external surface thereof is positioned adjacent the metering surface of the first metering chamber as a fluid under pressure is delivered therebetween, for thereby establishing a first annular orifice having empirically determined flow characteristics; E. a metering shaft having an axial conduit terminating in a plurality of radially directed terminal ports including a terminal protuberance of a conical configuration closing said axial conduit at a point adjacent to said ports and defining a second metering plug seated within the axial bore of said first metering plug in a manner such that the external surface of the second metering plug is related to the outwardly flared internal surface of the first metering plug for defining a fluid passageway therebetween, the axial position of said shaft being achieved concurrently with a delivery of a fluid through the conduit and said fluid passageway for thus establishing an annular discharge orifice having empirically determined flow characteristics; F. means defining a first weld seam coupling said shaft in place within said axial bore, whereby sAid shaft and said first metering plug fixedly are integrated into a unitary configuration; and G. means defining a second weld seam coupling said first metering plug to said plate for thereby fixedly integrating the plate and the metering plugs of said injector into a unitary, single-element coaxial injector. 